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Biomedical subjects

A Rocco

Publications and source records attributed to A Rocco.

At least 37 records · Page 2Linked to original sources
PubMed2000

Subdiffusive fluctuations of "pulled" fronts with multiplicative noise

We study the propagation of a "pulled" front with multiplicative noise that is created by a local perturbation of an unstable state. Unlike a front propagating into a metastable state, where a separation of time scales for sufficiently large t creates a diffusive wandering of the front position about its mean, we predict that for so-called pulled fronts, the fluctuations are subdiffusive with root mean square wandering Delta(t) approximately t(1/4), not t(1/2). The subdiffusive behavior is confirmed by numerical simulations: For t</=600, these yield an effective exponent slightly larger than 1/4.

Journal Article↗
PubMed2000

Interface dynamics in hele-shaw flows with centrifugal forces: preventing cusp singularities with rotation

A class of exact solutions of Hele-Shaw flows without surface tension in a rotating cell is reported. We show that the interplay between injection and rotation modifies the scenario of formation of finite-time cusp singularities. For a subclass of solutions, we show that, for any given initial condition, there exists a critical rotation rate above which cusp formation is suppressed. We also find an exact sufficient condition to avoid cusps simultaneously for all initial conditions within the above subclass.

Journal Article↗
PubMed2000

Pulmonary venous flow and mitral inflow velocity pattern in uncomplicated obesity: evidence for late diastolic dysfunction.

BACKGROUND: Active left ventricular relaxation, assessed by Doppler isovolumic relaxation time, is impaired in obesity. There is little information on left ventricular passive properties during filling. METHODS: To evaluate left ventricular late diastolic stiffness in obesity, Doppler echocardiographic interrogation of mitral inflow tract and pulmonary vein flow velocities were obtained from 47 normotensive, young obese subjects (11 males, 36 females) and 43 normotensive, young normal-weight volunteers (13 males, 30 females) of comparable age. RESULTS: After controlling the effect of blood pressure and left ventricular mass, isovolumic relaxation time was prolonged in obese subjects (p < 0.0001 vs normal-weight controls). No difference was found in transmitral peak early and late flow velocities. Obese subjects exhibited prolonged pulmonary vein reverse flow velocity during atrial contraction (p < 0.004), and a higher difference or ratio between duration of pulmonary reverse flow and duration of transmitral forward late flow (6 +/- 31 vs -20 +/- 39 ms or 1.06 +/- 0.3 vs 0.84 +/- 0.3, p < 0.002 and p < 0.001, respectively). These differences were also confirmed after controlling blood pressure and left ventricular mass. Non-invasively estimated left ventricular end-diastolic pressure was higher in obese subjects than in controls (p < 0.002). At multivariate analysis a higher body mass index was the sole predictor of prolonged difference between duration of pulmonary reverse flow and duration of transmitral forward late flow (beta = 0.38, p < 0.001). CONCLUSIONS: Obesity is associated with prolonged left ventricular active relaxation and abnormalities of filling pressure not detectable by the sole mitral inflow velocity pattern. These latter abnormalities are consistent with the presence of early increased left ventricular passive stiffness.

Adult↗
PubMed1999

The efficacy of octreotide therapy in chronic bleeding due to vascular abnormalities of the gastrointestinal tract.

BACKGROUND: The treatment of angiodysplasia and watermelon stomach, vascular abnormalities implicated in gastrointestinal bleeding of obscure origin, is a major clinical problem. AIM: To determine the efficacy of octreotide in patients with long-standing gastrointestinal bleeding due to acquired angiodysplasia and watermelon stomach, resistant to previous treatments and not suitable for surgery because of old age and/or concomitant disorders. PATIENTS AND METHODS: We treated 17 patients (seven had isolated angiodysplasia, seven had multiple upper and lower gastrointestinal angiodysplasia, and three had watermelon stomach) with octreotide (0. 1 mg subcutaneous t.d.s. for 6 months). Six of the patients had liver cirrhosis, one had Glanzmann-type platelet derangement, two had cardiovascular diseases and one had chronic uraemia. RESULTS: Octreotide treatment stopped bleeding in 10 patients. A transient improvement was observed in four, who needed subsequent cyclical retreatment to correct low haemoglobin levels. No effect was observed in three, probably due to the severity of the concomitant disorders. CONCLUSIONS: Octreotide is a safe drug that may be useful to control the recurrent gastrointestinal bleeding due to acquired angiodysplasia and watermelon stomach, especially in patients who are not candidates for surgery due to old age and/or concomitant disorders.

Adult↗
PubMed1999

Effect of Helicobacter pylori infection and its eradication on cell proliferation, DNA status, and oncogene expression in patients with chronic gastritis.

BACKGROUND: Helicobacter pylori, the main cause of chronic gastritis, is a class I gastric carcinogen. Chronic gastritis progresses to cancer through atrophy, metaplasia, and dysplasia. Precancerous phenotypic expression is generally associated with acquired genomic instability. AIM: To evaluate the effect of H pylori infection and its eradication on gastric histology, cell proliferation, DNA status, and oncogene expression. METHODS/SUBJECTS: Morphometric and immunohistochemical techniques were used to examine gastric mucosal biopsy specimens from eight controls, 10 patients with H pylori negative chronic gastritis, 53 with H pylori positive chronic gastritis, and 11 with gastric cancer. RESULTS: All patients with chronic gastritis were in a hyperproliferative state related to mucosal inflammation, regardless of H pylori infection. Atrophy was present in three of 10 patients with H pylori negative chronic gastritis and in 26 of 53 with H pylori positive chronic gastritis, associated in 18 with intestinal metaplasia. DNA content was abnormal in only 11 patients with atrophy and H pylori infection; eight of these also had c-Myc expression, associated in six cases with p53 expression. Fifty three patients with H pylori positive chronic gastritis were monitored for 12 months after antibiotic treatment: three dropped out; infection was eradicated in 45, in whom cell proliferation decreased in parallel with the reduction in gastritis activity; atrophy previously detected in 21/45 disappeared in five, regressed from moderate to mild in nine, and remained unchanged in seven; complete metaplasia disappeared in 4/14, and markers of genomic instability disappeared where previously present. In the five patients in whom H pylori persisted, atrophy, metaplasia, dysplasia, and markers of genomic instability remained unchanged. CONCLUSIONS: Chronic H pylori infection seems to be responsible for genomic instability in a subset of cases of H pylori positive chronic atrophic gastritis; eradication of H pylori infection can reverse inflammation and the related atrophy, metaplasia, and genomic instability.

Adult↗
PubMed1998

Does Helicobacter pylori play a role in inflammatory bowel disease?

The cause of inflammatory bowel disease is still unknown although several bacterial and viral agents have been implicated in their aetiologies. Helicobacter pylori infection, the main cause of gastroduodenal diseases, could, theoretically, be involved in the pathogenesis of inflammatory bowel disease. In fact, it induces permeability alterations and immunological derangements in the stomach similar to those detected in the colon of inflammatory bowel disease patients. However, epidemiological data do not support this hypothesis and recent evidence even points to a low prevalence of Helicobacter pylori in inflammatory bowel disease. These data are discussed in the light of possible confounding factors.

Adult↗
PubMed1996

[The effect of neoplastic hyperprolactinemia on bone density].

In young hyperprolactinaemic patients a reduction of bone mass density is frequently shown. However, until now the real mechanism has not been clarified (a direct role of PRL has been suggested). To better clarify the origin of the bone demineralization during hyperprolactinaemia we evaluated the BMD in a group of 24 proved PRL secreting pituitary adenomas. Based on menstrual characteristics the patients were subdivided in 3 groups: 1) oligomenorrhoea (OM), 2) amenorrhea lasting less than 2 years (AMa), 3) long-lasting amenorrhea (AMb). Twelve women with normal menstrual cycles served as controls. The BMD values at L2-L4 and thighbone levels were significantly reduced in the AMb group with respect to the other subgroups. The results support the hypothesis that BMD reduction in aPRL patients is secondary to hypoestrogenism and to the duration of amenorrhea rather than to hyperprolactinaemia.

Adenoma↗
PubMed1993

Effect of chronic bromocriptine treatment on psychological profile of patients with PRL-secreting pituitary adenomas.

Hyperprolactinaemic patients are characterized by an altered psychological profile, positively modified by the administration of dopaminergic drugs. This would suggest that the same neurochemical disorder is responsible for both hyperprolactinaemia and abnormal psychological profile in these patients. To identify depression, anxiety, and aggressiveness, nine women affected by prolactin (PRL)-secreting pituitary adenomas were studied before and after 6 and 12 mo of bromocriptine therapy, by the use of different psychometric tests (Mean Minnesota Multiphasic Personality Inventory [MMPI], State-Trait Anxiety Inventory [STAI], and State and Trait Aggressiveness Scale [STAS]). As a group, the patients did not show any depressive, anxious, or aggressive tendencies. Furthermore, no significant modifications were observed during dopaminergic treatment. Patients bearing PRL adenomas seem to be characterized by a dopaminergic background different from that found in functional hyperprolactinaemia. This hypothesis could explain the different psychological configuration and behavior in response to the administration of dopaminergic compounds.

Adult↗
PubMed1991

Effect of ritanserin, specific 5HT-2 antagonist, on PRL secretion in normal subjects and in different hyperprolactinaemic conditions.

The availability of a new specific anti 5HT-2 compound, ritanserin (RTS), led us to further investigate the role of serotonin in controlling PRL secretion. The drug was administered to normoprolactinaemic subjects and to patients with differing hyperprolactinaemic conditions. While RTS failed to modify PRL levels in normoprolactinaemic subjects and in patients with PRL-secreting pituitary adenomas, a marked decrease in the hormone was obtained in patients with functional and puerperal hyperprolactinaemia. The lack of effect of RTS in PRL-secreting pituitary adenomas suggests that the reported suppression of PRL by other antiserotoninergic drugs, such as metergoline, is probably due to their concomitant dopaminergic activity.

Adenoma↗
PubMed1989

[Cephalometric analysis in acromegalic patients].

The authors of the present work have done a cephalometric study on 11 patients affected by acromegaly. The target of this research was to obtain with cephalometric analysis a means for the follow up of the disease together with an important provisional parameter of growth of the face bones, helping thus to obtain an early diagnosis and the general lines for a correct therapy. With the data obtained has been extrapolated a table with average data of cephalometric angles that, transferred on to a tracing could represent the cephalometric prototype of an acromegalic patient.

Acromegaly↗
PubMed1987

Obesity as a risk factor for endometrial cancer.

The epidemiology and risk factors for endometrial cancer are reviewed, with current data. Obesity seems to be the main risk factor for this neoplasia, both because it is very common in the female population, and because the other risk factor (i.e. estrogen replacement therapy) has almost disappeared with the addition of progesterone therapy. The pathogenesis of obesity as risk factor, although it is not completely clear and unique, is examined.

Estrogens↗
PubMed1986

Inhibitory effect of bromocriptine treatment on luteinizing hormone secretion in polycystic ovary syndrome.

In order to investigate a possible common role of central dopaminergic mechanisms in the release of PRL and LH in patients with the polycystic ovary syndrome (PCO), plasma LH pulsatile profiles and the response to GnRH were studied in a group of 12 PCO patients before and after 3 months of treatment with bromocriptine, 2.5 mg twice daily. They were divided into two groups of six patients according to the occurrence or not of hyperprolactinemia (plasma PRL, 30.3 +/- 2.7 (SE) ng/ml vs. 9.5 +/- 0.8 (SE) ng/ml). Integrated LH secretion significantly decreased in hyperprolactinemic [2537 +/- 371 (SE) vs. 907 +/- 102 mIU/ml X min] as well as in normoprolactinemic (2847 +/- 460 vs. 901 +/- 152 mIU/ml X min) patients, but there was no difference in the response of the two groups. The LH increment after a bolus injection of 100 micrograms GnRH was reduced (P less than 0.01) to the same extent in both groups. These results indicate a dopaminergic component in the control of LH release in PCO patients, independent of the mechanism governing PRL secretion. Since bromocriptine reduced LH secretion, it may be useful for the management of this condition.

Bromocriptine↗
PubMed1983

Effect of long term administration of ovine prolactin on hypothalamic-pituitary testicular axis in rat.

The effect of hyperprolactinaemia on testicular morphology and on hypothalamic-pituitary-testicular axis was studied in adult male Wistar rats. Animals received ovine prolactin (oPRL) 200 micrograms twice daily s.c.) for 24 and 36 days and were killed by exanguination. Blood was collected for hormonal determinations and sex accessory glands were removed for histological studies. Circulating testosterone (T) and luteinizing hormone (LH) levels showed a significant reduction after 36 days of treatment whereas plasma follicle-stimulating hormone (FSH) levels were unchanged in all animals. No macroscopic or light microscopic histological modifications were observed in the testes. The present results, while excluding a direct effect of hyperprolactinaemia on seminiferous tubules, suggest that LH suppression is the consequence of a central effect of the ovine PRL long-term administration. The increased DA turnover in the hypothalamus suggested as inhibitory on GnRH neurons could account for this effect. The reduction of T levels seems to be mediated by the LH suppression, even though a direct effect of oPRL on Leydig cell receptors could be hypothesized.

Animals↗
PubMed1983

Reproductive parameters in prolactinaemic men.

The sexual behavior, hypothalamic-pituitary-testicular axis and seminal fluid parameters in three different models of hyperprolactinaemia were studied: patients with prolactin secreting pituitary adenomas, normal volunteers before and during metoclopramide, and psychotic patients on chronic neuroleptic therapy. Hyperprolactinaemia is always accompanied by a reduced seminal volume but there is no clearcut evidence that it can induce spermatogenesis modifications. Impotence is constantly present in the hyperprolactinaemic syndromes. The mildly impaired androgen production by the Leydig cells during hyperprolactinaemia does not seem to explain the impotence. Hypotheses on the pathogenesis of this symptom are suggested.

Adenoma↗